FIGS. 1A to 1C are a plan view, a cross sectional view, and a bottom view of a conventional angular velocity sensor, respectively, as shown in JP2010-160095A (Patent Document 1). This angular velocity sensor includes a flat plate-like diaphragm 101, a weight 103 located at a central portion of the diaphragm 101, a support portion 105 configured to support an outer peripheral portion of the diaphragm 101, an underlying electrode 107 formed on a surface of the diaphragm via an insulating film 106, a piezoelectric film 109 formed on the underlying electrode, and four vibration exciting electrodes 111 and four angular velocity detecting electrodes 113, both of which are formed on the piezoelectric film. To excite vibration having a motion component oriented in a predetermined direction of axis of vibration with respect to the weight 103, a vibration exciting portion composed of the four vibration exciting electrodes 111 is driven or excited. Displacement in a direction of axis of displacement of the weight 103 caused based on the Coriolis force is detected by the four angular velocity detecting electrodes 113 to obtain an angular velocity. In this angular velocity sensor, an origin O is defined to be located at the center position of the diaphragm 101 and an XYZ three-dimensional orthogonal coordinate system is defined such that the surface of the diaphragm 101 is included in an XY plane. Further, one of the X and Z axes is defined as the axis of vibration and the other as the axis of displacement. Then, an angular velocity around the Y axis is detected based on values detected by the four angular velocity electrodes 113 which define a displacement detecting portion. To detect angular velocities around the X and Y axes, the weight 103 should be vibrated in the Z-axis direction. To detect an angular velocity around the Z axis, the weight 103 should be vibrated in the X-axis or Y-axis direction.